Marine life rebounds dramatically in areas designated off-limits to fishing, according to the first comprehensive review of the impacts of marine reserves over time. Moreover, the effects are fast and long-lasting. And that's unexpectedly good news for ailing marine ecosystems, scientists say.
Although marine reserves are gaining popularity as a means to protect areas of the sea from overfishing and other human activities, much less than 1% of ocean waters is protected worldwide. And although it makes sense that ocean life would benefit from areas without the pressures of fishing, reserves were set up with little understanding of their actual effectiveness.
To determine how marine life responds to reserves, marine ecologists Ben Halpern and Robert Warner of the University of California, Santa Barbara, reviewed 81 studies that measured the biological health of 80 "no-take" reserves ranging in age from 6 months to 40 years. The results were striking: Overall, reserves boasted 20% to 30% more species, and the average size of fish and invertebrates was similarly greater, they report in the May issue of Ecological Letters. Populations were nearly twice as dense, and the total amount of living matter was nearly three times greater in reserves than in unprotected areas.
When the researchers analyzed the changes within individual reserves over time, they discovered something even more remarkable: The benefits of protection kicked in quickly and peaked within a few years. "Many species seem to be quite resilient when given a permanent refuge," Halpern says. The fast recoveries are very surprising, he adds, because most people expected that reserves would have to be in place for many years before the effects would be so obvious.
Charles Wahle, director of the Science Institute of NOAA's Marine Protected Areas Center, says the work "represents an important turning point in the national dialog about using protected areas to conserve our most important marine ecosystems." He says the findings present the most compelling and comprehensive evidence to date that marine reserves are effective within their boundaries.